Phenol In Aqueous Solution Research Articles

Triangular Shaped Graphene-Ag3PO4 Hybrid Nanocomposite: An Efficient Photocatalyst for the Degradation of Phenol under Visible Light Irradiation

Graphene-Ag₃PO₄ hybrid nanocomposite with the unique triangular morphology of Ag₃PO₄ is successfully fabricated by simple one pot hydrothermal method. The hybrid Graphene-Ag₃PO₄ nanocomposite photocatalyst was characterized by different advanced analytical instruments for morphological and physiochemical properties of material. The results are promising and nano Graphene-Ag₃PO₄ hybrid composite shows improved photocatalytic movement than pure Ag₃PO₄ for degradation of phenol. SEM shows the in-situ growth of finely distributed triangular shaped Ag₃PO₄ nanoparticles over the surface of graphene sheets. Production of .OH radicals on the Ag₃PO₄ surface was detected by the PL technique applying coumarin as an investigating chemical. The effect of graphene (from 10 to 50 wt %) loading in composite material on rates of degradation of phenol in aqueous solution was investigated. Among prepared catalysts an optimum 20 wt% graphene loading in hybrid nanocomposite visible light catalyst shown two times higher activity than pure Ag₃PO₄, further loading of graphene lowers activity.

Catalytic wet air oxidation of phenol by cordierite honeycomb washcoated with Al/Zr pillared bentonite in a plug flow reactor

Cordierite monoliths coated with Al/Zr pillared bentonite clay powder were synthesized and tested for catalytic wet air oxidation (CWAO) of phenol aqueous solutions in a plug flow reactor. The catalysts were characterized by using various techniques (EDS, SEM, BET and XRD), confirming the effective deposition of Al/Zr pillared bentonite clay on the channel walls of cordierite monolith. The composite catalyst showed good mechanical stability after ultrasound treatment. The performance of the composite catalyst was evaluated in a catalytic plug flow reactor for continuous oxidation of phenol in terms of catalytic activity as well as their stability. The composite catalyst achieved high catalytic performance (100 % phenol conversion and 91 % total organic carbon reduction) with high stability after 140 h long experiment. During the CWAO of phenol reaction, aromatic ring intermediates (p-benzoquinone, catechol and hydroquinone) and short-chain carboxylic acids (oxalic acid, maleic acid, formic acid, acetic acid and malonic acid) were identified. Kinetic parameters of the model that describes the formation and oxidation of intermediate aromatic compounds and short-chain carboxylic acids were determined. The obtained experimental data results were described sufficiently with respect to phenol conversion. The proposed CWAO of the phenol kinetic model accounts for internal and external diffusion limitations, assuming the pseudo-first-order reaction. Therefore, synthesized monolithic catalysts have great potential for application in CWAO of phenol, since the materials used in the process are inexpensive, abundant and require minimal modifications.

γ-Al2O3 doped with cerium to enhance electron transfer in catalytic ozonation of phenol

Ozone decomposition into free radicals, which can be facilitated by enhancing electron transfer between ozone and catalyst, is an important segment in catalytic ozonation. We doped cerium uniformly on γ-Al2O3 with an impregnation–calcination method to enhance electron transfer in catalytic ozonation of phenol in aqueous solution. The removal efficiency of phenol is raised from 39.7% by ozonation alone to 46.3% by catalytic ozonation with Ce/Al2O3 in 50 min reaction. A higher Ce3+/Ce4+ ratio in Ce/Al2O3 witnesses a higher electron transfer rate in catalytic ozonation and thus a higher degradation efficiency of phenol, illustrating that the activity of Ce/Al2O3 depends on the valence state of Ce. The electron transfer cycle is formed by the electron donation from Ce3+ to ozone molecule and the electron acceptance of Ce4+ from adjacent lattice oxygen. After getting the electron, the ozone molecule is decomposed to generate free radical of ·OH on the surface of Ce/Al2O3. The continuous flow experiments exhibit a stable and high catalytic activity of Ce/Al2O3 for catalytic ozonation, implying the feasibility in practical application.

Improved Photocatalyzed Degradation of Phenol, as a Model Pollutant, over Metal-Impregnated Nanosized TiO2.

Photocatalyzed degradation of phenol in aqueous solution over surface impregnated TiO2 (M = Cu, Cr, V) under UV-Vis (366 nm) and UV (254 nm) irradiation is described. Nanosized photocatalyts were prepared from TiO2-P25 by wet impregnation, and characterized by X-ray diffraction, X-ray fluorescence, transmission electron microscopy, UV-Vis diffuse reflectance spectroscopy, Raman spectroscopy, and adsorption studies. No oxide phases of the metal dopants were found, although their presence in the TiO2-P25 lattice induces tensile strain in Cu-impregnated TiO2-P25, whereas compressive strain in Cr- and V-impregnated TiO2-P25. Experimental evidences support chemical and mechanical stability of the photocatalysts. Type IV N2 adsorption–desorption isotherms, with a small H3 loop near the maximum relative pressure were observed. Metal surface impregnated photocatalysts are mesoporous with a similar surface roughness, and a narrow pore distribution around ca. 25 Å. They were chemically stable, showing no metal lixiviation. Their photocatalytic activity was followed by UV-Vis spectroscopy and HPLC–UV. A first order kinetic model appropriately fitted the experimental data. The fastest phenol degradation was obtained with M (0.1%)/TiO2-P25, the reactivity order being Cu > V >> Cr > TiO2-P25 under 366 nm irradiation, while TiO2-P25 > Cu > V > Cr, when using 254 nm radiation. TOC removal under 366 nm irradiation for 300 min showed almost quantitative mineralization for all tested materials, while 254 nm irradiation for 60 min led to maximal TOC removal (ca. 30%). Photoproducts and intermediate photoproducts were identified by HPLC–MS, and appropriate reaction pathways are proposed. The energy efficiency of the process was analysed, showing UV lamps are superior to UVA lamps, and that the efficiency of the surface impregnated catalyst varies in the order Cu > V > Cr.

Application of Nanocomposit Of Al2O3/Activated Carbon Prepared by Hydrothermal Process for Phenol Removal

<p>Nancomposite of Al<sub>2</sub>O<sub>3</sub>/activated carbon was prepared from the mixture of alumina oxide (Al<sub>2</sub>O<sub>3</sub>) and activated carbon from palm oil shell under the mixture of aquabidest and ethanol (1:1). The mixture was treated by hydrothermal process at 250 <sup>o</sup>C for 3 h. Resulted Al<sub>2</sub>O<sub>3</sub>/ activated carbon was characterized using SEM/EDX for studying the morphology structure of activated carbon and composite showing a like flower structure attached on the surface. The chemical compositions were 73.18%, oxygen 23.72%, aluminium 2.30%, dan silica 2.00%. The efficiency of composite was investigated for removal of phenol in aqueous solution. The maximum adsorption of phenol was obtained at pH 2, adsorbent weight 2 g, contact time 60 min and phenol concentration 100 ppm.</p>

Efficient degradation of phenol in aqueous solution by catalytic ozonation over MgO/AC

Phenol is one of the most common and poisonous water pollutants. Treating phenol-containing wastewater has been a challenge in recent years. MgO/Activated Carbon (AC) composites were prepared by the equal volume impregnation method for catalytic ozonation of phenol in water. MgO/AC composites were characterized by ICP, IR, XRD, SEM, TEM, BET and XPS analysis. MgO incorporated in the form of nano-crystal particles on the surface of AC. Prepared MgO/AC shows good catalytic performance for the removal of phenol and COD. Catalyst loading, pH and initial concentration of phenol solution on catalytic ozonation performance were studied. The catalytic performance of AC was significantly improved by the modification with a few amount of MgO. The results showed MgO provides additional active sites for the generation of hydroxyl radicals which is favorable for degradation of organic contaminants. The intermediate products were determined and the possible degradation pathway was put forward. MgO/AC shows a promising way to prepare efficient catalysts for the catalytic ozonation of organic polluted water.

Carbon-supported manganese for heterogeneous activation of peroxymonosulfate for the decomposition of phenol in aqueous solutions

Phenolic substances are harmful to humans and other living things, even at low concentrations. Therefore, phenol must be removed from water with the proper process. One of the most effective processes for degrading phenol is heterogeneous catalytic oxidation. Three carbon materials as supports were used to prepare manganese-oxide based catalyst (2.5% MnOx/ACP and 2.5% MnOx/ACN), and graphene oxide (2.5% MnOx/GO). These catalysts were tested for the degradation of phenol in aqueous solution using peroxymonosulfate as a source of sulfate radical. The physio-chemical catalysts were characterised by several characterisation techniques such as powder X-ray diffraction, N2-sorption (BET), scanning electron microscopy (SEM) equipped with Dispersive Energy X-ray Spectroscopy (EDS). In comparison to other catalysts, heterogeneous activation of peroxymonosulfate was more effectively done by 2.5% MnOx/ACP, resulting in a higher production rate of sulfate radicals. In the presence of a catalyst at 0.2 g and 1 g peroxymonosulfate in 500 mL solution at 25 °C, 90% total organic carbon (TOC) removal and phenol decomposition of 100% was achieved in 90 min with phenol concentration of 75 mg/L. First-order kinetics were followed by phenol decomposition with the energy of activation on 2.5% MnOx/ACP of 15.0 kJ/mol.

Extreme ultraviolet time-resolved photoelectron spectroscopy of aqueous aniline solution: enhanced surface concentration and pump-induced space charge effect

We present extreme ultraviolet (XUV) time-resolved photoelectron spectroscopy (TRPES) of an aqueous aniline solution. One-colour XUV-induced photoemission signal of aniline was observed with much greater intensity than expected from its molar fraction in the bulk solution, indicating that aniline is hydrophobically segregated on the liquid surface. The concentration dependence of the photoelectron intensity is found to be well correlated with the surface concentration of aniline estimated by surface tension measurements. Similar segregation was observed also for phenol in aqueous solution. The enhanced surface concentration of aniline makes its XUV-TRPES to be highly vulnerable to the pump-induced space charge effects (PISC). The PISC caused by a moderate pump intensity was not completely corrected using a simple mean field model, and reduction of the pump pulse intensity was necessary. The spectra measured at lower pump intensity were corrected for PISC, which enabled us to extract the information on the excited state dynamics of aniline in aqueous solution under 240 nm photoexcitation. Two components with lifetime on sub-ps and >100 ps timescales were determined, and the former is ascribed to the solvation dynamics in the S 1 state after the ultrafast internal conversion from the S 3 state and the latter to the subsequent population decay of the S 1 state.

Study of the adsorbent properties of nickel oxide for phenol depollution

Phenol and its derivatives are considered as dangerous pollutants due to these harmful effects on health and the environment. Treatment of the waters charged by these compounds by adsorption remains very important. For these reasons, this study was designed to prepare nickel oxide by precipitation method in order to remove these pollutants from aquatic environments. Indeed, structural and textural properties of this solid have been determined by various physicochemical methods (X-ray diffraction, Fourier transform in the infrared, N2 adsorption/desorption (BET), ATD / ATG thermal analysis and scanning electron microscopy (SEM)). In addition, several adsorption tests were carried out in order to show the effectiveness of this solid for the elimination of phenol in aqueous solution and to determine the physicochemical parameters which affect adsorption. Our results have shown 5.29 mg·g−1 of adsorption capacity with 98% of yield. Furthermore, it was shown that adsorption process was endothermic. For the kinetic study, it was demonstrated that phenol adsorption on NiO follows the pseudo-second-order and the Langmuir model better adaptable for the isotherm of desorption. Moreover, thermodynamic study shows positive values of ΔS ° (266.6 JK−1·mol−1) suggesting a randomness increase of the solid/liquid interface. ΔH ° (60.41 kJ·mol−1) was also positive confirming the endothermic nature of the adsorption processes. However, ΔG ° (kJ·mol−1) was negative suggesting the spontaneity of the phenol adsorption. In summary, this work suggests that phenol adsorption on NiO was linked to the chemical adsorbate/adsorbent interactions.

Carbonaceous material obtained from bark biomass as adsorbent of phenolic compounds from aqueous solutions

In this work, a novel carbonaceous material from Haematoxylum campechianum (C-HC) was obtained as an alternative adsorbent for eliminating phenol (Phen), 4-chlorophenol (4-ClPhen) and 4-nitrophenol (4-NPhen) from aqueous solutions. The carbonaceous material was prepared from bark biomass after phosphoric acid impregnation followed by thermal treatment at 500 °C for 60 min. The material was characterized by X-ray diffraction (XRD) and scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS). The textural parameters and the point of zero charge of the C-HC adsorbent were determined as well. The results show that the carbonaceous material was obtained as a mixed graphitized/amorphous phase. The major components of this material were carbon, oxygen, and in a minor amount, the phosphorous and sodium. The surface area, pore volume, and mean pore diameter of this material were 181.49 m2/g, 0.09396 cm3/g, and 2.07 nm, respectively, with a pHpzc of 7.02. To determine the optimal conditions and the maximum adsorptive capability of the obtained C-HC material against phenolic compounds, various conditions such as the contact time (15–180 min), initial adsorbate concentration (10–1000 mg L−1), C-HC dose (5–25 mg L−1) and solution pH (2–10) were investigated using batch experiments. The time to reach the equilibrium for 4-NPhen and 4-ClPhen was approximately 60 min, compared to 120 min for Phen. The experimental data fit well to the pseudo-second-order kinetic model (R2 ≥ 0.99) in all cases, and the kinetic constant of pseudo-second-order was highest for 4-NPhen (k2 = 0.075 g/(mg min). The experimental data of the isotherms were well fitted to Langmuir and Lui model. The maximum adsorption capacity (Qm) based on the Langmuir model was obtained for Phen (94.09 mg/g). The dose of the C-HC and the pH of the phenolic aqueous solutions influence the sorption capacity of the carbonaceous material. The best conditions to reach the maximum adsorption of the phenolic compounds were with a dose of 20 mg/L and at pH 2. The solubility, pKa and the dipolar moment of the phenolics affect notably the kinetic and the maximum adsorption capacity of the C-HC, considering that 4-Phen has the lowest solubility and pKa constant, and the highest dipolar moment.

A simple strategy based on fibers coated with surfactant-functionalized multiwalled carbon nanotubes to improve the properties of solid-phase microextraction of phenols in aqueous solution

Methods and experimentsIn this study, a functionalized multiwalled carbon nanotube (MWCNT)-coated solid-phase microextraction (SPME) fiber was developed for concentrating analytes in aqueous samples. Sodium deoxycholate (NaDC) was used as a dispersing agent for non-covalent modification of MWCNTs. The coating showed porous structure and large adsorption capacity. To investigate the capability of this MWCNTs/NaDC SPME fiber, it was applied to the analysis of phenols in aqueous solution. After extraction, the analytes were desorbed in an acetonitrile–water solution and analyzed using high-performance liquid chromatography.ResultsThe MWCNTs/NaDC fiber exhibited good analytical performance, and fine preparation reproducibility was obtained with the relative standard deviations (RSDs) ranging from 4.9% to 10.2% (n = 6) in one batch, from 5.7% to 11.9% (n = 3) among different batches. Under the optimum extraction conditions, the detection limits were 0.15–0.30 ng/mL(S/N = 3), the linear detection ranges were 1–100 ng/mL (R2 ≥ 0.9997) for these analytes, and good recoveries (80.3–95.4%) were obtained for the spiked samples.ConclusionThis is a simple and accurate pretreatment method for the analysis of phenols in aqueous samples.

Photocatalytic Degradation of Phenol in Aqueous Solutions Using TiO2/SiO2 Composite

Photocatalytic degradation of phenol in aqueous solutions was investigated using TiO2/SiO2 composites with different Ti/Si molar ratios (95/5(75/25) and calcined at 500 (C. The synthesized composites were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and N2 adsorption-desorption isotherms. Their photocatalytic activities for phenol degradation were evaluated in a batch reactor under simulated visible light using a special 26 W compact lamp. The results showed that all synthesized composites consist of pure anatase phase with high crystallinity and exhibit high photocatalytic activities for phenol degradation. At the initial concentration 10 ppm phenol and catalyst dose 0.10 g/L, the highest photocatalytic activity for phenol degradation was observed with the synthesized TS05 composite (Ti/Si molar ratio of 95/5), resulting in 53.5 % phenol degradation yield after 4 h. The corresponding phenol degradation yields using the synthesized composites TS15 (Ti/Si molar ratio of 85/15) was ~ 40.0 % and TS25 ((Ti/Si molar ratio of 75/25) was ~ 36.0 %. The TS05 composite could be a promising photocatalyst for the removal and degradation of organic pollutants.

Oxidative Destruction of Phenol in Aqueous Solution by Cotreatment with UV Radiation and Hydrogen Peroxide

The oxidative degradation of aqueous solutions of phenol by radiation with ultraviolet light and combined treatment with ultraviolet radiation and hydrogen peroxide has been studied. It has been found that the degree of oxidation of phenol by ultraviolet irradiation can be as high as 99.9%. It has been demonstrated that the initial pollutant and reagent concentrations have a significant effect on the degree of conversion and the rate of oxidation process. For the first time, the kinetic effect of phenol degradation has been experimentally revealed when phenol enters into the aqueous medium preliminarily irradiated with ultraviolet light. The products of the oxidative degradation of phenol have been identified and quantified.

Production and characterization of modified biochar by corn cob and its ability to absorb phenol

The adsorption performance of KOH modified biochar as adsorbent for phenol in aqueous solution was investigated. The effects of initial pH of the solution, initial concentration of phenol, contact time and temperature on the adsorption capacity of phenol were investigated. Adsorption isotherms, adsorption kinetics and thermodynamic analysis were examined. The results showed that the specific surface area of modified biochar was 487.64m2·g−1, the content of C is 72.06 wt.% and the value of H/C is 0.05, the aromatization degree of modified biochar is very high. The results showed that the maximum adsorption capacity of the modified biochar is 217.06 mg·g−1 at 298 K, which is higher than that of biochar. The adsorption process accords with the Freundlich adsorption isotherm model and pseudo-second-order kinetic equation. Thermodynamic analysis shows that adsorption is spontaneous and exothermic.

Scope of the DMC mediated glycosylation of unprotected sugars with phenols in aqueous solution.

Activation of reducing sugars in aqueous solution using 2-chloro-1,3-dimethylimidazolinium chloride (DMC) and triethylamine in the presence of para-nitrophenol allows direct stereoselective conversion to the corresponding 1,2-trans para-nitrophenyl glycosides without the need for any protecting groups. The reaction is applicable to sulfated and phosphorylated sugars, but not to ketoses or uronic acids or their derivatives. When applied to other phenols the product yield was found to depend on the pKa of the added phenol, and the process was less widely applicable to 2-acetamido sugars. For 2-acetamido substrates an alternative procedure in which the glycosyl oxazoline was pre-formed, the reaction mixture freeze-dried, and the crude product then reacted with an added phenol in a polar aprotic solvent system with microwave irradiation proved to be a useful simplification.

Synergy of Granular Activated Carbon and Anaerobic Mixed Culture in Phenol Bioremediation of Aqueous Solution

The present study focused on the synergistic effects bioremediation of phenol in aqueous solution using combination of anaerobic mixed culture and Granular Activated Carbon (GAC) as a biological GAC (BGAC). Meanwhile, the effect of contact time and various phenol concentrations on adsorption and biosorption process investigated. The phenol concentration was analyzed using UV/Vis spectrophotometer. The morphology and structure of two adsorbents (GAC and BGAC) were characterized by FESEM and BET specific surface area analysis. The batch experiments using mixed bacterial culture, isolated from wood and paper factory wastewater, were adapted to high concentrations of phenol and employed in order to evaluate the tolerance and biosorption capability of microorganisms for phenol biodegradation. The synergetic effect of phenol removal using combination of GAC with an anaerobic biofilm indicated that the removal efficiency for concentration of 700, 800, and 1000 mg/l at initial stages increased to 4, 10, and 12%, respectively and while by increment of the retention time did not shown significant impact on the removal efficiency. These results conducted both desorption of adsorbates due to biotransformation in the aqueous solution and direct assimilation of adsorbates on GAC by the microorganism’s biofilm. The adsorption data were fitted with pseudo-first-order and pseudo-second-order models and it was found that the pseudo-second-order model explains the adsorption kinetics more efficiently. The compatibility of the Freundlich and Langmuir adsorption models to equilibrium data were investigated. In fact, the Langmuir isotherm was found to be the best fitting isotherm.

Radiation-Assisted Waste Water Treatment Using Nanocatalyst and Fenton’s Reagent

The effect of nanocatalyst and Fentons reagent on the efficiency of wastewater treatment under the influence of -radiation was studied. Model samples of aqueous solutions of phenol were used for examining radiolytic decomposition patterns under the influence of -radiation (at doses in the range of 1.418 kGy) in the presence or absence of nano-gamma-Al2O3 catalyst accompanied by in situ Fentons reagent formation. It was established that the addition of the nanocatalyst to the system resulted in an increase in the rate of phenol decomposition and an increase in the radiation-chemical yields of the radiolytic transformation. Industrial and municipal wastewater samples were applied for studying possibility of their biochemical treatment under the influence of -radiation in the presence of the nanocatalyst and a component of Fentons reagent system. Irradiation of wastewater samples taken from an oil refining enterprise led to an enhancement of water quality and a substantial improvement in bacteriological parameters (indicators of E. coli and total microbial count). Изучено влияние нанокатализатора и реактива Фентона на эффективность очистки сточных вод под действием гамма-излучения. На модельных образцах водных растворов фенола установлены закономерности радиолитического разложения фенола в водных растворах под действием γ-излучения (при дозах в диапазоне 1.4-18 kГр) в присутствии и в отсутствии катализатора нано-гамма-Al2O3 при наличии образующегося in situ реактива Фентона. Установлено, что добавление в систему нанокатализатора приводит к повышению скорости разложения фенола и увеличению радиационно-химического выхода радиолитического превращения. На реальных пробах промышленных и коммунально-бытовых сточных вод показана возможность их биохимической очистки под действием γ-излучения в присутствии нанокатализатора и компонента реактива Фентона. Облучение образцов сточных вод нефтеперерабатывающего завода привело к улучшению качества воды и к заметному улучшению бактериологических параметров (показателей E. coli и общего микробного числа).

Antagonistic and plant growth promoting properties of actinomycetes from rhizosphere Deschampsia antarctica E. Desv. (Galindez Island, Antarctica)

Aim. The isolation of actinomycetes from Deschampsia antarctica É. Desv. (Galindez Island, Antarctica) rhisosphere and determine their ability to produce compounds with antimicrobial and plant growth promotional properties. Methods. Actinomycetes were isolated using the three different methods: direct inoculation, the roots treatment with an aqueous solution of phenol and heated at 100 °C for 60 minutes. To study the antibacterial activity of actinomycetes, they were plated on the Oatmeal medium and flooded by 0,7% agar with specific test-culture. Antifungal activities were studied by putting the agar block with fungal culture on Petri plates with cultures of actinomycetes. An activity index was determined by the ratio of the diameter zone of the inhibit growth test-cultures to the diameter of the actinomycetes colonies. Plant growth promotion properties were studied by commonly accepted methods. Results. 35 psychotolerant isolates were identified among the 43 actinomycetes isolated from D. antarctica rhizosphere. Almost 42% of actinomycetes isolates were antagonists at least one of typical strain of phytopathogenic bacteria (Pseudomonas savastanoi pv. phaseolicola, Xanthomonas campestris pv. campestris, Agrobacterium tumifaciens, Erwinia amylovora) or fungi (Fusarium oxysporum, Botrytis cinerea, Alternaria alternata). An activity index of most isolates was 3—6, in some isolates — 30—32. The potential plant growth promotion properties of isolates were evaluated. 11 isolates of actinomycetes produced indolyl-3-acetic acid (the level of synthesis was 21,0—62,5 μg/ml), 27 isolates produced siderophores and 6 isolates solubilized phosphorus compounds. Conclusions. Antimicrobial and plant growth promotional properties of the actinomycetes from rhizosphere D. antarctica were evaluated. Phytopathogenic bacteria and fungi antagonists were identified. A number of isolates were characterized by plant growth promotional properties that are combined with the synthesis of antimicrobial compounds. Such properties of isolated actinomycetes may play an important role in the adaptation of Antarctic plants to extreme conditions of existence. The described actinomycetes can be a source of new biologically active compounds and genes that control their biosynthesis.

Fabrication of electrospun polyethersulfone/titanium dioxide (PES/TiO2) composite nanofibers membrane and its application for photocatalytic degradation of phenol in aqueous solution

The main objective of this research is to use the photocatalytic properties of PES/TiO2 nanofibers membranes to remove the phenol as a toxic pollutant in various effluents. The uniform fibers in terms of minimum bead formation and fibers diameter were fabricated. Therefore, more TiO2 catalysts are on the surface of the fibers which increase the active surface area of nanoparticles and consequently improve the phenol degradation efficiency. The effects of TiO2 concentration on hydrophilicity, mechanical properties, porosity, mean pore size, and water flux of membranes were studied. The PES/TiO2 nanofibers were evaluated for phenol degradation under UVA irradiation through a transparent membrane module. The amount of removable phenol was analyzed with high‐performance liquid chromatography. Central composite design was used as a statistical experimental design. Finally, the effect of TiO2 content in nanofibers and initial phenol concentrations were investigated as well as pH values in synthetic wastewater, on phenol degradation. The results from analysis of variance (ANOVA) analysis indicated that TiO2 content in nanofibers was the most important and effective parameter on phenol degradation. It was also presented that there is no significant interaction between parameters so that the effect of each parameter was investigated separately. Maximum phenol degradation was 43.0 ± 0.3% and found under conditions of TiO2 content, initial phenol concentration, and pH value of 8%, 120 ppm, and 7, respectively.

Influence of operational parameters and kinetic modelling of catalytic wet air oxidation of phenol by Al/Zr pillared clay catalyst.

Single and mixed oxide Al/Zr-pillared clay (Al/Zr-PILC) catalysts were synthesized and tested for catalytic wet air oxidation (CWAO) of aqueous phenol solution under milder conditions, in a semi-batch reactor. The catalysts were synthesized from natural bentonite clay using ultrasonic treatment during the aging and intercalation steps and were characterized using High Resolution Scanning Electron Microscopy-Energy Dispersive angle X-ray spectrometry (HRSEM-EDX), powder X-ray diffraction (p-XRD), nitrogen adsorption/desorption, Fourier Transforms InfraRed Spectroscopy (FTIR) and zeta potential. Successful pillaring of aluminum and zirconium oxides into the clay was confirmed by p-XRD with increased basal spacing (1.92 nm) and higher specific surface area (230 m2/g). The influence of stirrer speed (200-1000 rpm), catalyst dosage (1-3 g/L), initial pH (1-3), initial phenol concentration (500-1500 mg/L), the effect of temperature (80-150 °C) and oxygen pressure (5-15 bar) was evaluated on phenol conversion and their reaction kinetics. At the optimum conditions of initial pH of 3, catalyst dosage of 2 g/L, initial phenol concentration of 1000 mg/L, reaction temperature of 100 °C, and oxygen pressure of 10 bar, the complete removal of phenol was achieved by Al/Zr-PILC within 120 min. The CWAO process was well-described by the first-order power rate law kinetics model. The apparent activation energy of the reaction calculated by Arrhenius equation was 21.306 kJ/mol.